The Lions have suffered a triple blow to their playing squad as Lionel Mapoe, Courtnall Skosan and Derick Minnie have all been ruled out of their Australasian tour.
Utility backs Mapoe (MCL),Skosan (Hamstring) and Minnie (concussion) returned to South Africa on Monday morning after suffering injuries in the 41-13 loss to the Waratahs in Sydney.
The trio will undergo further scans and tests upon their arrival back in South Africa.
The Lions have called Coenie van Wyk and Alwyn Hollenbach into the squad and they will fly to Perth on Monday evening to provide cover against the Force on Saturday.
After making a positive start to the season with two wins the Lions have now lost their last six Super Rugby matches.